karen daniels dept. of physics, nc state...

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Jamming Meets Experiments(Day 2: Theoretical Frameworks)

Karen DanielsDept. of Physics, NC State University

http://nile.physics.ncsu.edu @karenedaniels [email protected]

Boulder School 2017: Frustrated and Disordered Systems

http://nile.physics.ncsu.edu/

mailto:[email protected]

2https://xkcd.com/1867/

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quasi-2D experiments

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Photoelastic Inversion

optimize fringe pattern & force/torquebalance each disk

Daniels, Kollmer, Puckett. Rev. Sci. Inst. (2017)

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Network Science

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Writing Data as an Adjacency Matrix

Papadopoulos, Daniels, Porter, Bassett (on arXiv soon!)

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System 2D Domain 1D Curves

Efficiency of global signal transmission

Local geographic domains

Bottlenecks or centrality

Global Efficiency ModularityGeodesic Node

Betweenness

0D Particles

Local loop structures

Clustering Coefficient

Network science metrics for different scales

Bassett, Owens, Daniels, Porter. PRE (2012)

http://netwiki.amath.unc.edu/

http://netwiki.amath.unc.edu/

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Force Network Ensemble

● count equations & constraints # of degrees of →freedom

● friction – provides history-dependence

– changes the counting of valid states

Tighe, Snoeijer, Vlugt, van Hecke. Soft Matter (2010)

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Experiment Version of FNE

Kollmer & Daniels, Powders & Grains 2017

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i (1- std[

i])

std[i

]

i

Bi

Jonathan Kollmer

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Null Model Matters

Bassett, Owens, Porter, Manning, Daniels. Soft Matter (2015)

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Effect of Resolution

Parameter


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Gap Factor Hull Ratio


Huang & Daniels. Granular Matter. (2015)

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Network Measures Distinguish Exp/Sim


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Multilayer Networks

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Black = Higher Friction BathRed = Lower Friction Subsystem

Puckett & Daniels PRL (2013)Papadoploulos, Puckett, Daniels, Bassett. PRE (2016)

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Papa

dopl

oulo

s, Pu

cket

t, D

anie

ls, B

asse

tt. P

RE

(201

6)

21Papadoploulos, Puckett, Daniels, Bassett. PRE (2016)

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Configurational Entropy & Statistical Ensembles

“

”

Sam Edwards

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Edwards' Central Idea

smallest system volume

only one validconfiguration

larger volume

more validconfigurations

S=lnΩ(V )1X

=∂ S∂V

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Test the “Zeroth Law”Zeroth law

requirestemperatureequilibration

Does Xbath = Xsubsys

?low

friction

highfriction

Puckett & Daniels. PRL (2013)

James Puckett

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3 lighting schemes

white light

particle positions

polarized light

contact forces

fluorescence

identify low-friction

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Pist

on

Pistongravity

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Local Voronoï Volumes


3 example histograms (for subsystem only)

sample Voronoï tessellation

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Plot the Overlapping Histograms


log

slope difference in compactivity→

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Compactivity Fails to Equilibratered (low-friction system) and black (high-friction bath) do not

have the same compactivity

Puckett & Daniels PRL 2013

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Compactivity Fails to Equilibratered (low-friction system) and black (high-friction bath) do not

have the same compactivity

Puckett & Daniels PRL 2013

explanation? equiprobability of jammed states only holds at jamming

Martiniani, Schrenk, Ramola, Chakraborty, Frenkel. Nature Physics (2017)

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Quantifying Interparticle Forces

d⃗ mn

f⃗ mn

particle m

particle n

Σ̂=∑m ,n

d⃗ mn f⃗ mn

force-moment tensor

Σ̂=V σ̂ Γ=Tr Σ̂

pressurestress tensor

Bi, Henkes, Daniels, Chakraborty. Ann. Rev. Cond. Matt. (2015)

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Photo Vector Forces Pseudo-photo→ →

Daniels, Puckett, Kollmer. Rev. Sci. Inst (2017) http://github.com/jekollmer/PEGS

Σ̂=∑m ,n

d⃗ mn f⃗ mnp=12(σ1+σ2)

τ=12(σ1−σ2)

grain scale force- moment tensor:

σ̂= ∑cluster

Σ̂

decompose into normal, deviatoric:

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Constraints on Interparticle Forces

What do you know about the 5 black arrows?

Bi, Henkes, Daniels, Chakraborty. Ann. Rev. Cond. Matt. (2015).

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Force Balance Tiles→

Bi, Henkes, Daniels, Chakraborty. Ann. Rev. Cond. Matt. (2015).

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Conservation: Maxwell-Cremona tile area

Tighe & Vlugt JSTAT 2010.

Sarkar, Bi, Zhang, Ren, Behringer, Chakraborty. PRE 2016

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Represent Whole Packing in Force Space

moving this point corresponds to adjusting the contact forces

in a way that preserves force balance

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Forces Field Theory→

● define a vector gauge field h(x, y) on the dual space of voids (, )

● going counterclockwise around a grain, increment the height field by the contact force between the two voids:

Ball & Blumenfeld PRL (2002) DeGiuli & McElwaine PRE (2011) Henkes & Chakraborty PRL (2005) PRE (2009)

h⃗∗= h⃗+ f⃗ lm

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Relationship to Continuum Mechanics

● forces are locally balanced is conserved→● Cauchy stress tensor can be calculated from the

height field: σ̂=∇⃗× h⃗

Σ̂=V σ̂

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Caveat: friction can cause non-convexity

Sarkar, Bi, Zhang, Behringer, Chakraborty. PRL (2013)

karen daniels dept. of physics, nc state...

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